Cooling device for electric apparatus



March 31, 1931. ROEBEL 1,798,702

COOLING DEVICE FOR ELECTRIC APPARATUS Filed May 12, 1927 externally of the tanks,

Patented Mar. 31, 1931 UNITED STATES LUDWIG ROEBEL, -OF MANNHEIM,

PATENT OFFICE GERMANY, ASSIGNOR T0 AKTIENGESELLSCHAFT BROWN BOVERI & 0113., OF BADEN, SWITZERLAND, A JOINT-STOCK COMPANY 01 SWITZERLAND COOLING DEVICE FOR ELECTRIC APPARATUS Application filed May 12, 1927, Serial No. 190,760, and in Germany May 31, 1926.

This invention relates to electrical apparatus of the type wherein the working parts are maintained immersed in oil for insulating and cooling effects. Types of such apparatus are transformers, reactances and the like.

The general purpose of the present invention is the provision of an apparatus for obt aining the desired circulation of the oil between the tank chamber in which the apparatus is housed and radiating devices in conjunction with the tank through which the oil is passed for the purpose of dissipating heat therefrom.

A particular object of the invention is the provision of apparatus of this type which is simple in construction and reliable in operation and which utilizes circulation of the oil by both convection flow and mechanical propulsion.

Another object is the provision of apparatus of the character above-mentioned wherein the circulation by convection may be carried on while the mechanical circulat- 1113' means is idle, and the latter brought into operation whenever occasion demands.

Another object is the provision of apparatus of the type indicated which may be incorporated with tanks of present design without involving material alteration or modification of the tank structure.

A further object is the provision of apparatus of the character specified in which the mechanically operated means are disposed where they are accessible for inspection or repair without requiring opening of the tanks or interruption of the operation of the electrical apparatus.

Other and further objects of the invention will be pointed out hereinafter or will be aparent to one skilled in the art upon an understanding of the invention or its employment in practice.

In the drawing forming a part of this specification, I illustrate, in diagrammatic fashion, one arrangement of apparatus embodying the invention, but it is to be understood that this is presented simply by way of example and is not to be accorded any in t-erpretation having the effect of limiting the claims short of the true and most comprehensive scope of the invention in the art.

In the drawing, the figure is a diagrammatic illustration partially in section and partially in elevation of apparatus embodying the invention, the same being a trans former tank having attached radiators for dissipation of heat from the oil, and mechanical means for inducing circulation of oil between the tank of the radiators.

The nature of the invention will be ascertained most quickly by immediate reference to the illustrative embodiment shown.

In the drawing, the reference character 10 designates a transformer tank housing a transformer 11 within a body of oil, said tank being closed by cover 12 through which the leading-in bushings 14 conduct the leads 15 of the transformer. Mounted on the side Walls of the tank are the radiators 16, of which there may be any appropriate number. The respective radiators constitute closed casings or receptacles having communication with the tank adjacent the upper portion thereof by way of connections 17, and adj acent the lower portion thereof by the connections 18. The radiator 16 may be formed with corrugated walls or provided with fins affording extensive heat transfer surfaces exposed to ex ternal air for expediting the dispersal of heat from the oil within them. The con nections 17 and 18 are in open communication with the chamber of the tank 10 and are of proper size to permit circulation of oil between the radiators and the tank by convection, the warmer oil at the top of the tank passing into the radiators through the connections 17, and the cooler oil from the radiators passing into the bottom of the tank through the connections 18. I11 the upper portion of the tank is disposed a distributing header 19 which'is supplied by a pump 20, disposed externally of the tank and drawing its supply from the upper portion of the tank through the pipe 21. The header 19 supplies a plurality of ejector devices 22 associated with the respective outlet connections 17 said ejector nozzles being constructed to eject oil at a velocity such as to induce an accelerated circulation of oil from the transformer tank through the radiators. Obviously, the ejector nozzles may be disposed in other relationships to the outlet connections than those shown, and the pump 20 may be arranged to serve a plurality of separate tanks or headers. The pump is driven by a suitable motor disposed externally of the tank, the operation of which motor may be controlled by thermostatic means responsive to temperature changes of the oil in the tank.

The apparatus functions as follows: Incident to the operation of the electrical apparatus 11, a certain amount of heat, depending largely upon the load on the apparatus, is generated, which heat is taken up by the surrounding oil. The warmer oil rises to the top of the oil body, and passes into the radiators 16 through the open outlet connections 17, while the oil in the radiators 16, being cooled by transfer of its heat through the air cooled walls of the radiator, circulates downwardly and returns to the tank through the open inlet connections 18. Thus a circulation between the tank and radiators takes place by convection. For expediting this movement of the oil, as in instances in which a considerable quantity of heat is being generated by the electrical apparatus, the pump 20 may be put into operation to draw oil from the upper portion of the tank and to supply it under an increased pressure to the header 19, from which it is ejected at increased velocity through the nozzles 22 within the body of oil. The oil thus e ected entrains warm oil from the upper portion of the oil body and carries it into the radiators at a velocity substantially greater than that occurring in the normal convection flow. This expedites the circulation of oil through the'radiators, so that cooled oil is supplied to the body about the electrical apparatus at an increased rate.

In addition to the advantages pointed out above, the disposal of the pump exteriorly of the tank avoids the additional heating of the oil by such heat as is generated by the operation of the pump.

The invention is'susceptible of incorporation with transformer tanks and thelike of various designs now in common use without involving material alteration, and its simplicity of construction is of material advantage in obtaining reliable operation. A further important feature resides in the fact that the mechanical oil circulating means does not promote the circulation of sludge or sediment from the bottom of the tank through the body of oil about the electrical apparatus.

It is to be understood that, in the foregoing description and the following claims, I use the term oil in a general or .generic sense, to designate any kind of liquid appropriate for use as a circulating cooling medium in apparatus of the type indicated.

lVhat I claim is:

1. In electrical apparatus, in combination, a tank for housing an electrical device in a body of oil, a radiator having communication with the tank adjacent its upper and lower portions by flow connections afiording circulation of oil between the two by convection, a pump disposed exteriorly of the tank and having supply connection with the upper portion of the tank chamber, and a device supplied by said pump for ejecting oil in a direction to induce flow of oil from the upper portion of the tank into the radiator.

2. In electrical apparatus, in combination, a tank for housing an electrical device in a body of oil, a radiator having communication with the tank chamber adjacent the upper and lower portions thereof by flow connections accommodating circulation of oil between the two by convection, an ejector device associated with the upper flow connection, and means operable exteriorly of the tank for supplying oil to said ejector device.

3. In electrical apparatus, in combination, a transformer tank and laterally associated radiator, upper and lower flow connections providing open flow communication between the upper and lower portions of the tank and radiator, an ejector arranged to discharge through the upper flow connection," and means exteriorly of the tank for supplying oil from the upper portion of the tank to said ejector.

4. In apparatus of the character described, a tank provided with an outlet opening, a radiator element disposed eXteriorly of said tank and communicating therewith by way of said opening, a fluid connection disposed within said tank and having an outlet portion directed toward and arranged adjacent said outlet opening and in spaced relation to the wall portion of said tank adjacent said opening, and means operable to provide for the flow of cooling fluid through said connection toward said opening.

In testimony whereof I have hereunto subscribed my name this 22d day of April, A. D. 1927, at Stuttgart.

LUDWIG ROEBEL; 

